Electrochemical Performance of Engineered NiCo₂O₄ in AEM Water Electrolyzers: Direct-Growth vs Spray-Coated Anode

This study investigates the synthesis and electrochemical performance of NiCo₂O₄ anodes for water electrolysis in both alkaline and anion exchange membrane (AEM) configurations. An engineered direct growth method using a urea-mediated sono-hydrothermal approach was used to synthesize NiCo₂O₄ on Ni felt, creating a binder-free electrode optimized for an alkaline environment. We evaluated the electrode's performance in AEM water electrolysis, comparing it with a spray-coated electrode incorporating ionomers and the same electrocatalyst. Our findings highlight that direct-grown binder-free electrodes, produced through varied synthesis routes, exhibit remarkable activity and stability in AEM cells operated in dry cathode mode (1.90 V @ 1 A cm^-2), with seamless interaction between the catalyst layer and the membrane. Moreover, this binder-free NiCo₂O₄ on Ni felt is also an efficient anode under alkaline electrolysis configuration, exhibiting high stability and remarkable performance (1.78 V @ 1 A cm^-2, 1.92 V @ 2 A cm^-2), ascribable to the increased conductivity and improved charge transfer resistance of the catalyst layer.